The present invention relates generally to container conveying systems and more particularly to a conveying system for open-ended containers utilizing a plurality of pins extending outwardly from a continuous conveyor chain powered by a chain drive.
In automated food and beverage packaging, many different conveyor systems may be used in a series of operational steps in decorating containers prior to insertion of a food product and sealing of the containers. One application for which the present invention is particularly suited is that of can decorating. In a typical can decorating operation, cylindrical cans having one open end are fed into a high speed, continuous can printer which prints ink images onto the cylindrical outer surfaces of the cans. After printing, the cans follow a circular path of travel at the periphery of a mandrel wheel. Transfer devices such as suction cups or the like are mounted on a transfer wheel which is provided at a location proximate the mandrel wheel. The transfer devices are used to transfer the cans from the mandrel wheel to a plurality of pin assemblies provided in spaced apart relationship on a pin conveyor chain. One such pin assembly enters each can while it is supported on the transfer wheel. Upon removal of suction from the transfer wheel suction cups, the pin assemblies support the associated cans received thereon and convey the cans away from the transfer wheel and through a drying oven or other remote area for further handling and processing. Such can decorating systems are well known in the art and are described in Sirvet U.S. Pat. No. 4,037,530 issued July 26, 1977; Talbott U.S. Pat. No. 4,129,206 issued Dec. 12, 1978; McMillin et al, U.S. Pat. No. 4,138,941 issued Feb. 13, 1979; and Stirbis U.S. Pat. No. 4,267,771 issued May 19, 1981, all of which are hereby incorporated by reference.
A problem with pin assemblies used on such pin conveyor chains in the past has been that the pin assemblies, in order to prevent damage to the conveyor chain, have been constructed so as to break when encountering an obstruction. When such pin breakage occurs, especially if a series of pins are broken, the conveyor chain must be stopped and the broken pins must be replaced.
Such repairs maybe very costly in terms of lost production time of the can decorating system. Such systems generally run at speeds on the order of 500 to 1000 cans per minute and thus a down time of even a few hours is extremely expensive. Replacement of such broken pins may be costly in terms of material and labor needed to perform the maintenance operation.
It would be generally desirable to provide a pin assembly which would reduce system maintenance expense and operating expense by providing essentially maintenance-free operation. Such a pin assembly should be capable of stablely supporting cans or other open-ended containers under all normal operating conditions. The pin assemblies should be deflectable, however, when encountering a fixed obstruction in order to allow the pin chain to continue operating without damage to either the pin assembly or the conveyor chain. The pin assemblies should further be self-seating so that after initial deflection the pins resume the normal can carrying configuration.